4X5 TMax 400/TMaxRS & Brown Stain Problem

I would be interested in communicating with anyone using the combination of large format TMax 400 film & TMax RS developer.

In the same batch, developed 12 sheets at a time in a Jobo tank, some film clears just fine while other sheets have this weird light brown stain that is noticable in the clear film-base-plus-fog area. Kinda like a coffee stain on white teeth. Fresh fixer was used so it is not that.